A new study says nearly two-thirds of New Orleans homes and yards have “dangerous” levels of lead, according to federal standards, a finding the authors believe may be linked to the extensive renovation and demolition of homes after Hurricane Katrina.

Times-Picayune archiveMost of the properties surveyed were built before 1946. Lead-based paint was not banned until 1978.

And unlike past studies of lead exposure in New Orleans -- which found that children most at risk of elevated blood lead levels were African-American, from low-income families, and living in rental housing -- the new study found the high levels are not linked to race or income.

The age of a home is the most relevant factor in whether lead levels on the property are too high, the study found. Most of the houses surveyed were built before 1946. Lead-based paint was not banned until 1978.

“New Orleans children are at risk for elevated blood lead levels, including children who were not considered at high risk previously and for whom lead reduction has been considered a public health success,” the study concluded. It was published online last week in Environmental Health Perspectives.

The study points out that while both federal and state laws bar sanding lead-based paint during renovations, loopholes in those laws and lax enforcement likely led to the increased lead contamination, the study found.

“There is need for enhanced surveillance and lead hazard mitigation efforts to safeguard the health of New Orleans residents,” the study concluded. “The current targeted screening and public health intervention efforts to prevent childhood lead poisoning may need to be expanded to capture a population that previously was not considered at risk of environmental lead exposure.”

Tulane epidemiologist Felicia Rabito, who led the study, said efforts to test the lead levels of all children in the city must be stepped up, either by requiring such testing for admittance to the city’s schools, or by pressuring primary care physicians to do such testing.

But screening alone won’t stop the problem, she said.

“We need people in the city to understand the risk of lead poisoning and take ownership,” Rabito said. “If they see someone sanding, they should ask them to stop and inform them of the dangers, and then inform the city.

An earlier study of lead levels in soil in 2006 — soon after Katrina, but before much of the rebuilding — found lead levels lower than they were in a similar study that sampled yard soils between 1998 and 2000.

The latest study measured lead levels in dust on bare floors and window sills in 109 households throughout the city, and at the surface of bare soil. Those are places where young children are most likely to get dust on their hands and feet and then into their mouths.

High levels of lead in the blood can affect the central nervous system, kidneys and blood cells. Effects can include reduced IQ, hyperactivity, reduced stature, hearing problems and headaches.

While lead poisoning symptoms can include diarrhea, stomach cramps, lethargy, vomiting or seizures, those symptoms are rare, which is why the Centers for Disease Control and Prevention recommends screening lead levels in children ages 1 to 6.

Because of its old housing stock and the historic contamination of lawns from lead in gasoline, New Orleans has long had a high number of children with elevated lead. In 2004, a year before Katrina, 13.8 percent of all children tested in the city had levels above 10 micrograms per deciliter, the level considered lead poisoning by the Centers for Disease Control. In 2009, that level had fallen to 5.3 percent.

The exact reason for the drop is unknown, but given the 2006 soil test results, some scientists attributed it to sediment washed into the city during Katrina.

The incidence of elevated blood-lead levels in other New Orleans-area parishes is much less common, ranging from 0.5 percent of those tested in St. Bernard Parish to 2.2 percent in Plaquemines Parish.

The new Tulane study collected data on lead as part of a larger study of mold and allergens in the aftermath of Katrina. The researchers used Sewerage & Water Board records to identify reoccupied residences, and used a random method to contact 109 homeowners in nine of the city’s 13 planning districts. They didn’t include Village de L’est, Venetian Isles and English Turn because they are not considered part of the city’s “urban core.” They also excluded the Lower 9th Ward, since few people had returned to that area at the time the study effort began.

The majority of respondents, 62 percent, were white and had an annual household of $30,000 or more. The majority of homes tested were built prior to 1946; 69 percent of participants were homeowners.

The researchers found an average level of soil lead of 560 parts per million, compared to 408.1 parts per million in the 1998-2000 survey. A soil level of 400 parts per million is defined as dangerous by the federal Environmental Protection Agency.

The survey found 51 percent of homes had at least one elevated interior sample, and 47 percent of homes had bare soil that met the “dangerous” threshold. Levels greater than 1,200 parts per million, three times the federal standards, were found in 27 percent of the yards surveyed.

Rabito said those suspecting problems with lead in their homes should consider having the house and yard tested. Sweeping or vacuuming lead dust is not recommended, she said. Instead, wet mopping, with the mop rinsed in clean water before re-use, will collect the lead dust.

She recommends that the first 2 1/2 inches of soil from contaminated yards be removed before being replaced with uncontaminated dirt. Growing grass or vines atop bare spots also will reduce the potential for exposure.